If you have no LN configured, they can't zap you. Please ask your somebody about details. Where is the zap? Details of the LN payment.

Zaps I think work as follows:

1. Alice clicks on Bob's ⚡

2. Bob's LN node creates an invoice (Maybe with amount and comment as per Alice' request)

3. Alice pays invoice

4. LN node emits a zap nostr event containing the optional comment and the optional payer pubkey

(Now what I wonder is how do we know how real these zap events are. Can't Eve send zap events claiming that Alice zapped a billion bitcoin? Do clients handle negative amounts correctly?)